Isolation of nucleic acids from samples such as cells, tissues, plants, bacteria, viral particles, blood, serum, or plasma may be an important step for genetic analysis. Conventionally, liquid phase extraction techniques, such as phenol/chloroform precipitation, are widely used. Although these approaches may yield nucleic acids of high quality, they can be laborious, time-consuming, and highly operator-dependent. Solid phase extraction techniques are a popular alternative. They are often the methods of choice when processing large numbers of samples. Commonly used solid-phase substrates include, for example, silica spin columns and silica magnetic particles that may provide large surface areas for nucleic acid binding. These porous matrices and micro/nano particles, however, may induce nucleic acid shearing as a result of flow and particle mixing, leading to decreased nucleic acid integrity.
The dominant methods of nucleic acid extraction, such as DNA extraction, have remained remarkably unchanged since spin columns and magnetic microparticles were first introduced. While methods such as spin columns and magnetic microparticles are fast and easy, the shear forces imposed by these methods may fragment the nucleic acids and may be incapable of sufficient nucleic acid quality for the new generation of long read length sequencing and genome mapping technologies. As such, there exists an unmet need to develop novel separation materials and methods that allow for easier isolation and purification of nucleic acids from biological samples.
Thermoplastic substrates have previously been disclosed that contain a hierarchical structure of microscale folds layered with nanoscale silica lamella that are easily fabricated using an inexpensive heat-shrinkable polyolefin (PO) film. This nanomembrane can be fine-tuned to create a non-porous, high surface area binding substrate capable of capturing vast amounts of nucleic acids without imparting nucleic acid fragmenting shear forces. By minimizing fragmentation, it may be possible to bias nucleic acid binding away from a prone conformation towards a tentacle conformation, increasing binding capacity to, for example, about 100 to about 1,000,000 times greater than previously reported for silica microparticles. Furthermore, the silica nanomembranes use a simple bind, wash, and elute protocol that combines the ease of column and bead extraction with the performance of phenol-chloroform, resulting in nucleic acid yields that can be about 10 times greater than either columns or magnetic beads and nucleic acids of high purity and high molecular weight.
To facilitate extraction of large amounts of high quality, high molecular weight nucleic acids from cells, tissues, and body fluids, disclosed herein is a magnetic silica nanomembrane material made by depositing a magnetic component on or embedded in a thermoplastic substrate in addition to at least one silica layer. The magnetic silica nanomembrane enables extraction to proceed analogously to a magnetic process whereby a magnet can be used to draw the nanomembrane to a side or bottom of a container, such as a test tube, thereby facilitating pipetting and washing without disturbing the nanomembrane or the bound nucleic acids.
Disclosed herein are inexpensive magnetic thermoplastic nanomembrane materials that use a hierarchical layering of micro- and nanoscale silica lamella and a magnetized layer to create a high surface area and low shear substrate capable of capturing vast amounts of high molecular weight nucleic acid without fragmentation.